Once he gets that second foot down, it's in Blandino's hands.
After two feet down, all he has to do is hold onto the ball long enough to become a runner. How long that is ultimately depends on the judgment of the league's head of officiating, who oversees all reviews. Blandino said he had it long enough to become a runner. So he's a runner. Touchdown.
Even under last year's rules, the "football move" would not have applied to Tate's catch, as it occurred in the end zone, where no football move is needed. Last year, the question would have been, "Did he hold onto the ball long enough to make a football move, thus becoming a runner?" while this year it's shortened to "Did he hold onto the ball long enough to become a runner?" That makes sense in the end zone, where no football move is needed, and it applies to the famous Calvin Johnson play.
Dez's catch did not occur in the end zone, so under last year's rules, they did have to look for a football move. They said he didn't make enough of one, because he didn't reach with two hands, or extend his arm toward the goal line. Neither of those explanations makes sense, of course.